Sheet-folding machine



June 19, 1956 R. G. DEXTER SHEET-FOLDING MACHINE 8 Sheets-Sheet 1 FiledJune 19, 1952 IN VEN TOR.

June 19, 1956 R. G. DEXTER SHEET-FOLDING MACHINE 8 Sheets-Sheet 2 FiledJune 19, 1952 HVVENTUR. F Aek'f' ('7- DCGEI- June 19, 1956 R. G. DEXTERSHEET-FOLDING MACHINE 8 Sheets-Sheet 3 Filed June 19, 1952 June 19, 1956R. e. DEXTER 2,751,222 SHEET-FOLDING MACHINE j. -9+-L chum.

attorneg June 19, 1956 R. G. DEXTER SHEET-FOLDING MACHINE 8 Sheets-Sheet5 Filed June 19, 1952 INVENTOR. 706414 6. D4 0%,.

June 19, 1956 DEXTER 2,751,222

SHEET-FOLDING MACHINE Filed June 19, 1952 8 Sheets-Sheet 6 INVENTOR.ROIe -f E 1 June 19, 1956 R. G. DEXTER SHEET-FOLDING MACHINE 8Sheets-Sheet 7 Filed June 19, 1952 INVENTOR.

June 19, 1956 R. G. DEXTER SHEET-FOLDING MACHINE 8 Sheets-Sheet 8 FiledJune 19, 1952 United States Patent SHEET-FOLDING MACHINE Robert G.Dexter, Lexington, Mass., assignor, by mesne assignments, to Barkley &Dexter, Incorporated, Fitchburg, Mass., a corporation of MassachusettsApplication June 19, 1952, Serial No. 294,307

8 Claims. (Cl. 27081) This invention relates to a sheet-folding machine.

In general the object of the invention is to provide a novel, efficientand superior sheet-folding machine, adapted for use in automaticallyfolding sheets, such as towels and the like, in an accurate, rapid andpractical manner.

Another object of the invention is to provide a folding machine of thecharacter specified wherein provision is made for forming one or moreparallel folds in the sheet and for thereafter forming one or more foldsat right angles to the first folds in a novel and superior manner.

With these general objects in view, and such others as may hereinafterappear, the invention consists in the sheetfolding machine and in thevarious structures, arrangements and combinations of parts hereinafterdescribed and particularly defined in the claims at the end of thisspecification.

In the drawings illustrating the preferred embodiment of the invention,Figs. 1 and 1A taken together comprise a view in side elevation of thepresent sheet-folding ma chine; Fig. 2 is an end view of the machine asseen from the left of Fig. 1A, some of the parts being broken away tomore clearly illustrate the transfer mechanism; Figs. 3, 4, 5 and 6 areperspective views illustrating the sequence of the folding operationsperformed on the present machine; Fig. 7 is a plan view of the transfermechanism; Fig. 8 is a side elevation of the same showing the transfermechanism in its upwardly rocked position; Figs. 9 and 10 are views infront and side elevations respectively of the tucking mechanism; Fig. 11is a detail view in side elevation of the folding or tucking arm; Fig.12 is a detail view I in side elevation of a portion of the transfermechanism; j Fig. 13 is a cross-sectional view taken on the line 1313,..of Fig. 12 illustrating connecting elements for the transfermechanism; Figs. 14 and 15 are cross-sectional views similar to Fig. 13showing the transfer elements in different positions of operation; Fig.16 is a detail view of brake mechanism associated with the transfermechanism; Fig.

117 is a side elevation of a differential timing unit forming :a part ofthe control mechanism, some of the parts being :shown in cross section;Fig. 18 is a cross-sectional view taken on the line 18-18 of Fig. 17;Figs. 19, 20, 21 and 22 are diagrammatic views of a folding station andillus- Irating a sheet in different positions of advancement relative tothe control mechanism for effecting folding of the sheet; Fig. 23 is adetail view of the timing mechanism shown in a different position ofoperation; and Fig. 24 is a wiring diagram of the control mechanismembodied in the present sheet-folding machine.

In general the present invention contemplates a sheetfolding machinehaving a plurality of successive folding mechanisms for formingsuccessive folds in the sheet and wherein each folding mechanism isarranged to be automatically operated through control means including aphoto-sensitive detector arranged to detect the passage of the leadingand trailing edges of the sheet during its advance into foldingposition; and a differential timing mechanism responsive to thedetecting means and arranged to actuate the folding mechanism when thesheet has been advanced through a predetermined and selected distancerelative to the folding mechanism whereby the sheet may be accuratelyfolded in one-half, one-third or other selected proportion of its lengthirrespective of the length or variations in the length of the sheet.

in the illustrated embodiment of the invention the distance between thephoto-sensitive detector and the folding member is fixed, and inoperation, when the leading edge of the sheet trips the photo-sensitiveelement, the timing mechanism is caused to rotate at one rate of speedrelative to the advance of the sheet, and when the trailing edge of thesheet passes the detector, the timing mechanism is caused to rotate atanother rate of speed relative to the advance of the sheet, the totalrotation of the timing mechanism being fixed and related to the fixeddistance between the detector and the folding member. As a resuit, thetiming mechanism effects actuation of the folding member at apredetermined and selected point proportionate to the length of thesheet, such proportion being maintained irrespective of the length ofthe sheet. For example, when the sheet is to be folded in half, thetiming mechanism is caused to rotate at one-half speed relative to theadvance of the sheet so that when the sheet has traveled its full lengthrelative to the detector, the timing mechanism has rotated through aproportionate distance equal to one-half the length of the sheet. Atthis time, the centerline or fold line of the sheet is disposed one-halflength beyond the detector. When the trailing edge of the sheet passesthe detector, the timing mechanism is caused to rotate at full speedrelative to the advance of the sheet, and since the remaining travel ofthe sheet to dispose the centerline thereof in alignment with thefoldingmember is related to the remaining rotation of the timing mechanism toeffect operation of the folding member, the latter will be operated tofold the sheet in half. The sheets may be similarly folded inone-quarter or one-third by merely changing the initial speed of thetimer to rotate one-quarter speed or one-third speed respectivelyrelative to the advance of the sheet as will be hereinafter more fullydescribed.

The present sheet-folding machine may and preferably will comprise alower folding section arranged to form one or more parallel folds, andan upper folding section arranged at right angles to the lower foldingsection, and novel transfer means is provided for transferring the sheetfrom the lower section to the upper section, the transfer operationforming a fold at right angles to the first section. Succeeding foldsmay be made during the progress of the sheet through the upper foldingsection whereupon the completely folded sheet may be delivered from themachine.

Referring now to the drawings, in general the present sheet-foldingmachine includes a plurality of receiving belts 10 upon which a sheet tobe folded is place to be advanced into operative position to a firstfolding station, indicated generally at 12, arranged to automaticallyfold the sheet intermediate its length as determined by the advance ofthe sheet past photo-sensitive detecting means 14 forming a part of thecontrol mechanism to be described. The once-folded sheet is thenadvanced past a second photo-sensitive detector 16 and into operativerelation to a second folding station, indicated generally at 18,arranged to automatically form a second fold parallel to the first foldat an intermediate point in accordance with the operation of the controlmechanism associated with the photo-sensitive detector 16. Thetwicefolded sheet is then advanced along conveyor belts 20 intooperative relation to a transfer and third folding station, indicatedgenerallyat 22. During its advance to the transfer station 22, thetwice-folded sheet passes a third photo-sensitive detector 24 formingpart of control mechanism for actuating the transfer mechanism todeliver the sheet into an upper folding unit, indicated generally at 26,and disposed transversely to the lower or initial folding unit, thetransferring operation forming a third fold at right angles to thepreviously formed folds. The sheet is then advanced past a fourthphoto-sensitive detector 28 and into operative relation to a fourthfolding station, indicated generally at 30, arranged to form a finalfold parallel to the third fold whereupon the completely folded sheet isdelivered out of the machine on conveyor belts 32.

As herein shown, the receiving conveyer comprises a series oftransversely spaced and relatively narrow parallel belts arranged to runthe full length of the machine over an idler roller 34 disposed at thereceiving end of the machine, as shown in Fig. 1, and a driving roller36 disposed at the other end of the machine, as shown in Fig. 1A. Theidler roller 34 may be journalled in belt-tightener bearings 38adjustably supported in guides 40 formed in the machine frame. As shownin Figs. 1A and 2, the driving roller 36 is arranged to be continuouslydriven through connections including a motor 42, variable drivemechanism 44, gear-reduction unit 46 and sprocket and chain drive 48connected to the drive shaft 50.

The upper run of the receiving conveyor 10 may pass over a supportingtable 52, as shown in Fig. l, and the sheet to be folded may be placedon the conveyer with one edge thereof in alignment with an adjustableguide member 54 for aligning the sheet in predetermined relation to thetransfer mechanism for performing the third fold, as will be described.

As illustrated in Fig. l, the first told is performed by a tucking orfolding arm 56 fast on a rocker shaft 58 journalled in suitable bearingsin the machine frame. As illustrated in detail in Fig. 11, the tuckingarm 56 is provided with a plurality of spaced fingers 60 arranged toextend between the belts 10 when the arm is rocked upwardly to engageand lift a medial portion of the sheet into the bight of cooperatingbelt conveyers 62, 20 running over spaced rollers supported above thereceiving conveyer 10, each conveyer 62, 29 likewise comprising a seriesof spaced parallel belts. As herein shown, the belt conveyer 62 isarranged to run over a driving roller 66 and an idler roller 68 suitablyjournalled in the machine frame. The cooperating conveyer 20 is arrangedto run under idler roller 69, over roller 66 with the belts incooperating engagement with the belts 62, and around roller 70, theupper run of the belts 20 extending to the end of the machine, as shownin Fig. 1A, and passing around roller 72 and belt-tightener rollers 74,76 back to the idler roller 69. Suitable belt guides, indicated at 78,may be provided to maintain the belts in predetermined spaced relation,each guide comprising a transversely extended angle bar provided with aplurality of upstanding curved spacers 80 extended between the belts, asshown. The end roller 72 may also be provided with a plurality of spacedcollars 73 defining grooves in which the belts 20 are guided.

In the illustrated embodiment of the invention, the first fold is formedalong a medial line to fold the sheet in half, as shown in Fig. 3, thefolded sheet being supported and advanced between the continuouslydriven belts 62, 20 until it arrives in operative relation to the secondfolding station 18. The second fold is performed by a tucking or foldingarm 82 similar in construction and mode of operation to the firstfolding: arm 56. In operation the arm 82 is rocked upwardly to engageand lift the once-folded sheet along a medial line into the bight ofcooperating belts 20 and 84 running over spaced rollers disposed abovethe conveyer 62 to again fold the sheet in half, as shown in Fig. 4. Thebelts 20 pass around roller 70, as described, and the belts 84 arearranged to run over idler roller 36 and driving roller 88, the lowerrun of the belts 84 cooperating with the upper run of the belts 20 toadvance the folded sheet therebetween, as illustrated. It will beunderstood that the above-described first and second folds areautomatically effected through control mechanism to be described tocause operation of their respective folding arms 56, 82 at predeterminedpoints with relation to the length of the sheet in accordance withtiming mechanism actuated by the detection of the leading and trailingedges of the sheet as it passes the photo-sensitive devices 14, 16respectively.

The twice-folded sheet is then advanced on the belt conveyer 20 past thephoto-sensitive detector 24 and into operative relation to the transfermechanism 22. As herein shown, the transfer mechanism 22 comprises aparallel linkage including parallel arms 90, 92 and link 94 arrangedlongitudinally of the belt conveyor 20. The transfer linkage is normallydisposed in a lowered position, as shown in Fig. 1A, and when actuatedby the passage of the leading edge of the twice-folded sheet past thephoto-sensitive detector 24, the transfer linkage is rocked upwardlybetween adjacent belts 20 to engage an intermediate portion laterally ofthe sheet, and to insert the same into the bight of cooperating belts96, 32 running over spaced rollers to form the third fold at rightangles to the first two folds, as shown in Pig. 5.

It will be observed that the line of the third fold may be predeterminedby initial placement of the sheet at the receiving end of the conveyer19, one edge of the sheet being aligned with the guide member 54, seeFig. 2, the latter being adjustable relative to the centerline of thelongitudinally extended transfer linkage 22 to produce a fold in thedesired predetermined position.

In practice the transfer linkage 22 is rocked upwardly and rearwardlyopposite to the direction of travel of the belts 20, and in order toavoid carrying the sheet rearwardly during the transfer operation and toprovide a substantially vertical transfer movement, a compensatingparallel linkage is provided comprising parallel arms 10% pivotallyconnected to the transfer link 94 and connecting link 162. Theconnecting link 102 is connected at one end by a link 104 to a bracket106 attached to the machine frame so that in operation when the transferarms 90, 92 are rocked clockwise viewing Fig. 8, the compensating armsare caused to rock counterclockwise, thus counteracting the tendency ofthe transfer unit 22 to carry the sheet rearwardly during the transferoperation.

Furthermore, in order to prevent the laterally extended ends of thefolded sheet from being pulled forwardly on the continuously movingbelts 20 during the transfer operation, a plurality of relativelyshorter parallel linkages, comprising elevating linkages 107, 109,disposed on both sides of the transfer linkage, are arranged to berocked from a position below the belts 20 to a position slightly abovethe belts, the shorter linkages operating simultaneously with thetransfer linkage to form an elevated support for the lateral ends of thesheet during the transfer operation. As shown in Figs. 2, 7 and 8, eachelevating linkage includes parallel arms 108 and connecting link 110,and in practice, the transfer linkage is immediately returned to itslowered position while the supporting linkages are permitted to remainin their upwardly rocked position until the trailing edge of one side ofthe sheet passes beyond the photo-sensitive detector 24 and into theupper folding unit 26 whereupon the supporting linkages are returned totheir lowered position, as will be described.

As illustrated in Fig. 2, the cooperating belts 96, 32 between which thetwice-folded sheet is inserted to form the third fold forms a part ofthe upper folding unit 26, such belts also comprising a plurality ofrelatively narrow spaced belts running over adjacent rollers andcooperating to support and advance the folded sheet therebetween.

As herein shown, the conveyer belts 9.6 are arranged to run over roller112, idler roller 114, and driving roller 116, and the cooperatingconveyer belts 32 are arranged to run under roller 118, over theadjacent roller 112 and around a driving roller 120 disposed to presentthe lower run of the belts 32 in cooperative engagement with the upperrun of the belts 96, as shown. The upper run of the conveyer belts 32comprising the delivery conveyer extends over an idler roller 122 andback to the roller 118.

The sheet being advanced between the belts 96, 32 is carried past thephoto-sensitive detector 28 and into operative relation to the fourthfolding station 30 which may comprise a tucking or folding arm 124similar in construction and mode of operation to the first folding arm56. In operation the folding arm 124 is rocked upwardly to extend thefingers 126 between the spaced belts 96 and to insert the sheet into thebight of cooperating belts 32 and 128, the fold being preferably made todispose the extended portion of the sheet under the third foldedportion, as illustrated in Fig. 6. The belts 128 are arranged to runaround a driving roller 130 disposed adjacent the roller 120 and aroundan idler roller 132 disposed to present the lower run of the belts 128in cooperating engagement with the upper run of the belts 32. Thecompletely folded sheet carried along between the belts 32, 128 is thendelivered out of the machine on the conveyer belts 32.

Referring now to Figs. 1 and 1A, the first and second folding units 12,18 are arranged to be operated by similar tucker operating unitsindicated generally at 134, 136 respectively, and the transfer mechanism22 is likewise arranged to be operated by a similar operating unit 138,and such operating units as well as the various belts and rollerscomprising the lower folding section for forming the first two folds andthe transfer operation are arranged to be continuously driven by oneendless chain 140 arranged to run around a driving sprocket 142 fast onthe drive shaft 50. It will be observed that the drive roller 36 for thereceiving conveyer belts is mounted on the shaft 50, and starting at theleft-hand end of Fig. 1A and following the upper run, the driving chain140 extends from the drive sprocket 142 to a sprocket 144 driving thetransfer operating unit 138; then under a. sprocket 146 driving theroller 66 for the belts 62; over sprocket 148 driving the roller 88 forthe belts 84; around idler sprocket 150; around sprocket 152 secured tothe roller 70 for the belts over sprocket 154 driving the second foldoperating unit 136; under and over idler sprockets 156, 158respectively; under sprocket 160 driving the first fold operating unit134; over idler sprocket 162 and then back to the driving sprocket 142.

The upper folding unit 26 is likewise driven through connections fromthe main driving shaft 50 as illustrated in Figs. 1A and 2 wherein theshaft 50 is connected by a chain and sprocket drive 164 to a shaft 166upon which the roller 72 is mounted, and a second chain and sprocketdrive 168 connects the shaft 166 to a shaft 170. The driven sprocket 172is loose on the shaft 170 and forms the driving member of a manuallyengageable clutch, the driven member 174 being keyed to the shaft andmanually slidable into and out of operative engagement for the purposeof rendering the upper unit inoperative when only two folds are desiredin the sheet. The shaft 170 is connected by bevel gears 176, 178 to across shaft 18!) upon which the roller 130 for the belts 128 is mounted.The driving roller 120 for the belts 32 is driven from the cross shaft180 by spur gears 182; the driving roller 116 for the belts 96 is drivenfrom the shaft 180 by a chain 184 running over sprockets 186, 188 andidler sprockets 190, 192; and the tucker operating unit indicated at 194for operating the fourth folding mechanism 30 may be connected to theshaft 170 by a chain and sprocket drive 196.

From the description thus far it will be observed that the machine iscontinuously driven and that in operation fast on the tucker arm shaft.

.detecting means,

a sheet placed on the receiving conveyer 10 is continuously advancedthrough the machine and automatically folded at successive stations toform a completely folded sheet which is delivered from the machine onthe delivery conveyer 32. In accordance with the present invention, eachtucker operating unit is arranged to be selectively and automaticallyoperated to effect folding of its sheet at a predetermined and selectedpoint relative to its length by control mechanism including thephoto-sensitive detecting means actuated by the passage of the leadingand trailing edges of the sheet to operate a dilferential timingmechanism, one of which is indicated generally at 198 and which isconnected to electro-responsive means arranged to operate its respectivefolding mechanism.

As illustrated in Figs. 9 and 10, each tucker operating mechanism issimilar in construction and mode of operation so that a description ofone unit will sufiice for all. As herein shown, each tucker operatingunit includes a one-revolution clutch, indicated generally at 200,operatively connected to a shaft 202 journalled in suitable bearings204, 206 attached to a side frame 208 and to an outboard bracket 210extended from the side frame respectively. A earn 212 fast on the shaft202 is arranged to cooperate with a roller 214 carried by an arm 216Thus, in operation when the one-revolution clutch 200 is operativelyengaged, the cam 212 will make one revolution to rock its tucking armupwardly to perform the folding operation, the cam causing the arm to beimmediately returned to its lowered position. The one-revolution clutch200 may be of any usual or preferred design having a driving element 218loosely mounted on the shaft 202 and formed integrally with the drivesprocket over which the drive chain runs. The driven element 220 of theclutch may be keyed to the shaft 202 and is arranged to cooperate with asolenoid operated latch bar 222 pivotally mounted at 224 and having a.shouldered portion 226 arranged to engage: a cutout portion 228 of theclutch to disengage the same.

The latch bar 222 is urged in a counterclockwise direction viewing Fig.9 by a spring 230 to effect disengage ment of the clutch, and the lowerend of the bar is con--- nected by a link 232 to a solenoid 234 arrangedto be: energized at a predetermined time, as will be described,. to rockthe bar clockwise and permit engagement of the clutch 200. In operationthe bar 222 is immediately released to effect disengagement of theclutch at the end. of one revolution. In order to prevent backlash ofthe: shaft 202 when the shaft is brought to rest, a spring-- pressedpawl 236 pivotally mounted at 238 is arranged! to engage a notch 240formed in a ring 242 attached to the cam hub.

As illustrated in Figs. 1 and 2, each folding unit 12, 18, 30 isprovided with its individual timing mechanism: 198, 199, 201respectively, the transfer operating unit 22 being operated without atiming mechanism, as will be described. As illustrated in detail inFigs. 17 and 18,, each differential timing unit includes a cam disk 250haw ing a cutout 251 arranged to cooperate with a roller 252 carried byan arm 253 forming a part of a stop switch 254. The cam disk 250 is alsoarranged to cooperate with a second roller 255 carried by an arm 256forming part of an adjustable limiting switch 258 for closing a circuitto the solenoid 234 for releasing the one-revolution'clutch to elfectoperation of the tucking or folding arm at a predetermined time duringthe advance of the sheet.

The cam disk 250 is' mounted to rotate on a shaft 260 and is provided oneach side with magnetic contact disks 262, 264 arranged to cooperatewith independently driven magnetic clutches 266, 268 respectively, alsomounted to rotate on the shaft 260, the clutches 266, 268 being rotatedat different speeds and arranged to be selectively energized to attractand rotate the cam disk 250 at one speed or the other as'determined bythe photo-sensitive as will'be described. The cam disk 250a is.providedwith abushing270 and is freely rotatable;- on a spacingsleeve272 interposed between the two magnetic clutches266; 268, and in orderto reduce the effect of residuaLmagnetisrn when one clutch isdeenergized and. the other energized, relatively thin brass spacers 274,276 may be provided between the contact disks and their respectiveclutches.

The supporting shaft 260 is mounted in bearings formed in side frames278, 28f) of the differential timing unit, and as shown in Fig. 17, themagnetic-clutch element 268 is arranged to be drivenat a relatively fastspeed through spur gears 282, 284 having a ratio of one to oneconnectingthe clutch element to a drive shaft 286 rotatably mounted in the sideframes. The other clutch element 266 is arranged to be driven from theshaft 286 through a train of gears indicated at 288 at a relativelyslower speed, preferably at a definite ratio relative to, the magneticclutch 268, such as one-half, one-third or other ratio relative to thespeed of the opposing clutch element 268, the gearing 238 being designedto permit interchange and adjustment of selected gears to obtain thedesired relative speed.

The shaft 286 may be driven from the main drive of themachine, as shownin Fig. 1, through a chain and sprocket drive 290 connecting rollershaft 292 to a countershaft 294; and a chain and sprocket drive- 2%connecting the shaft 294% the shaft 286. Adjacent timing units 19?,201may be connected to the shaft 286 through chain and sprocket drives298, 300 respectively.

In operation the magnetic clutches 266, 263 of each unit arecontinuously driven in definite timed relation to the advance of theconveyer belts ofthe sheet-folding mechanisms through the drivingconnections described, and each magnetic clutch 266, 268 is arranged tobe energized through the usual brushes 3G1, 302 and 303, 304 supportedin an insulating block 305 for engagement with contact rings 396, 307and 383, 309respectively. The contact brushes may be connected incircuits arranged to be selectively closed by firing of thephotosensitivedetecting element as effected by the passage of theleading and trailingedges of'the sheet to be folded, as will behereinafter more fully described.

As illustrated in Fig. 18, the stop switch 254 is fixedly mounted in abracket 310 attached to the base of the timing unit. The roller arm 253is pivotally mounted in the bracket and is urged upwardly by a spring3R2 supported between an extended portion of the bracket and theunderside of the arm. A stud 314 adjustably carried in the arm 253 isarranged to engage the stop switch 254. The limit switch 258 is arrangedto be adjusted radially of the cam disk 25%, and as herein shown ismounted on a U-shaped bracket 316, the legs of the U being secured tocollars 317, 318 fast on the supporting shaft 26 A worm gear 32%) faston the shaft 269 is arranged to mesh with a worm 322 fast on the end ofa vertical stud 324 rotatably mounted. in a bearing 326 formed in theside frame 280. The stud is held in position by upper and lower collars327, 328- and a knurled knob 330 is provided-at the upper end of thestud. Thus, in operation the position of the limit switch relative tothe stop switch maybe adjusted tothe desired position foreffecting-folding of the sheet at a predetermined point as willpresently appear.

The operation of the present. sheet-folding mechanism isdiagrammatically illustrated in Figs. 19 to 22 showing the first foldingstation 12 with the sheet to be folded, as indicated at 8,. in differentpositions relative to the photo-sensitive detector 14 and the tucker arm56, and in Figs. 18 and 23 which illustrate the different positions ofthe timing cam 250 withrelation to the advanceof the sheet onthereceivingconveyer 10.v As shown in Fig. 19, the distance from thephoto-sensitive detector 14 to the' centerline of thetuckervfingerstdl)comprises apredeterminedand-fixed distance, indicated by theletter x,andthe trawl piitheibeltltl throughsuchfixeddistanceds definitee 1y.relatedto the arcuatedistance travelled by the cam of the. limit switch258-.during. the. same period of time,

such arcuate distance being indicated'by the letter y in. Fig.- 23'.Inotherwords, the distance travelled in inches by the-belt-lt) per unitof time is related to the distance travelledinxdegrees per unit of timeof the cam disk 250. For example, if itis assumed that the fixeddistance x is 31 /2 inches and the arcuate distance y is 315", each 1of. travel of the belts 10. will beequal to 10 of arcuate movement ofthe cam-.disk250. Now, if the length L of the sheet to be folded isassumed to be 48", and it is desiredtofoldthesheet centrally or exactlyin half, when" theleading'edgeofihe'sheet Scuts olf the light source. ofthezdetectorl i, a circuit .is closed to energize the slowlyrotatedimagnetic clutch 266' which through the gearing 28S: isarrangedinthepresent example to travel at onehalf thenormal speed relative to.the belt travel, or in other words, at a rate-of 5 for 1" of belttravel. The clutch element 266- thus energized attracts the earn 250 tocauserotation thereof with the. clutch 266 so that during the travel-totthe sheetthrough its full length of 48" past the detector 14; the'camdisk.250 is rotated through an angulardistance which-in the presentexample comprises aldistance of 4S' S' or 240. Simultaneously with thestart of thez-cam-diskt2s0, thestop. switch 254 is operatedto close aholding circuit, as will be described, and when the cam disk 250" hastravelled through the 240 the trailingendofthe sheet'isin alignment withthe detector 14 as. shown invtFig; 20 and the centerline of the 48"sheet is 24" distant: from the detector, that is one-half thelength-ofzthe sheet indicated by L/2 in Fig. 20. Now, sincethe fixeddistance xis 31 /2", the remaining distance for the sheetto'travel todispose the centerline thereof in alignmentwith the tucker 56 is 31/2"-24" or 7 /2".

During the; continued advance of the sheet, when the.

trailing-edge thereof passes beyond the detector 14 to again exposethedetector to the light source, the circuit to the magnetic clutch266is opened and another circuit is closedrtoenergize: the 1 to .1 speedmagnetic clutch 268, thus attracting the cam disk 250 to traveltherewith at a rateof 10- breach 1' of belt travel. Thus, since the camdisk- 250- has'already travelled 240 and the total travel toeifecttripping .of the limit switch is 315, the remaining. travelof :the diskis 315 240 'or which at the-rateof 10 per one inch of belt travel willeffect tripping .of:the.li'mit switch 258 when the sheet has travelled.the remainingzW/z to align: the center of the sheetwith .th'eifoldi'ng;arm56. Closing of theswitch 258' is arranged to energize the .tuckerunit solenoid 234 to release the oneirevolution:clutchiand permitthe'cam 212 to makeone :revolution toperform the tucking operation, asshown; in Fig. 21. To complete the cycle of operation, the camdislo250continues its rotation through the vremaining 45 toitsstartinggposition,.thus operating the stopswitch 254 to open thecircuit to the clutch 268 and causing th'e: cam disk to come :torest, asshown in Fig. 18. Fig: 22 shows the tucker arm 56 'returneditoits'initial position andthe folded sheet beingadvanced' between the-.belts62, 20 toward the second folding station 18, as diagrammaticallyindicated in Fig. 19.

In-another' example, assumingthat the sheet to be folded isa36 inches:in: length, during :the passage of the 36*inch. length .pastthe-detector 14, the earn 250 will be rotated atone-half the normalspeed so that when the trailing edge of the sheet reaches the detectorthe center-' line ofthe; sheet will be 18 inches beyond the detector andethetcam; will have travelled 180 of the 315 total.

leaves the detector,.the cam will be causedto rotate at full speed; andwhen. the cam has rotated the remaining of the 315 total, thecenterlineof the sheet'willbe:

aligned.withrthecfoldingstation and the tucker-operatedgtotperfomrthefdlding operation;-

In practice the fixed distance x and the related arcuate distance y maybe arbitrarily chosen with regard to the maximum length of the sheet tobe folded. For example, the fixed distance of 31 /2 inches willaccommodate any sheet up to a maximum of twice this distance or 63inches if the sheet is to be folded centrally. If the fixed distance xis changed, the arcuate distance y may be correspondingly changed byadjustment of the limit switch 258 relative to the cam in the mannerdescribed. If the sheet is to be folded in thirds, the ratio of thegearing 288 for the magnetic-clutch element 266 may be changed to eifectrotation of the cam 250 at A of normal speed during the passage of thesheet past the detector 14. Thus, if a 36" sheet is to be folded inthirds, the cam 250 will have rotated 120 when the folding center is 12inches beyond the detector and 19 /2 inches from the tucker. Then,during the full-speed portion of the cycle, the sheet travel of 19 /2inches will correspond to an arcuate movement of 195 to trip the limitswitch 258 to perform the folding operation. It will be apparent thatthe sheet thus folded in /3 at the first folding station may be foldedin /2 at the second folding station to complete the folding of the sheetin thirds.

The second folding station 18 and the fourth folding station 30 aresimilar in construction and mode of operation to the first foldingstation 12 described, each being provided with a differential timingunit 199, 201 respectively associated therewith so that furtherdescription thereof is thought unnecessary. The transfer or third foldstation 22 does not require a timing unit since the line of fold atright angles to the first and second folds is determined by initialplacement of the sheet on the receiving conveyer relative to theposition of the transfer bar as described. However, the passage of theleading edge of the twice-folded sheet to intercept the light source ofthe photo-sensitive element 24 is arranged to trip the transferoperating unit 138 to perform the transfer operation as described.

Referring now to Figs. 7 and 8, for a more detailed description of thetransfer mechanism 22, the connecting elements between the transferlinkage 22 and the sheetelevating linkages 107, 109 are arranged topermit the transfer linkage to be immediately returned to its initialposition after the transfer operation while the elevating linkages 107,109 are permitted to remain in their upwardly rocked position until thelonger edge 111 of the two laterally trailing edges of the sheet passesbeyond the photo-sensitive detector 24. As illustrated in Fig. 8, theparallel arm 90 of the transfer linkage 22 is pinned to a cross shaft350 supported in the machine frame and is arranged to be rocked by thetransfer operating unit 138. The other parallel arm 92 connected by thebar 94 is loosely mounted on a parallel cross shaft 352. As shown inFig. 12, the hub of the transfer arm 90 is provided with clutch teeth354 arranged to cooperate with similar teeth 356 formed in the elongatedhub 358 of the elevating linkage 109 on one side of the transferstation, and a collar 360 also pinned to the shaft 350 is provided withsimilar teeth 362 arranged to cooperate with teeth 364 formed in theelongated hub 366 of the adjacent elevating linkage 107 on the otherside of the transfer linkage, such elongated hubs 358, 366 being looselymounted on the shaft 350. The corresponding elongated hubs 368, 370 arepinned to the cross shaft 352 as indicated at 372, 374 in Fig. 7. Asshown in Fig. 12 the grooved portions 376, 378 of the pinned collar 360and arm 90 are cut longer than the teeth 364, 356 respectively so as topermit relative movement of the transfer linkage with respect to theelevating linkage. Thus, when the parts are in their lowered position,as shown in Fig. 13, the teeth 362 of the collar 360 are in contiguousengagement with the teeth 364 of the hub 366, the teeth 354, 356 beingsimilarly engaged so that when the shaft 350 is rocked clockwise toperform the transfer operation, the elevating units 107, 109 aresimultaneously rocked 10 as indicated in Fig. 14. The transfer linkageimmediately returned to its initial position by upwardly, 22 is thenvirtue of the transfer operating mechanism 138 while the mechanismsremain in their upwardly rocked trailing edge 111 of the sheet passesbeyond the photo detector 24, see Fig. 2. As shown in Fig. 7, the shaft352 to which the hubs 368, 370 are pinned, is provided with an arm 380fast thereon arranged to cooperate with a solenoid operated latch 382,as illustrated in detail in Fig. 16. The latch 382 is pivotally mountedat 383 and is urged into latching position by a spring 384 so that inoperation when the transfer unit is rocked the arm 380 is retained inits rocked position to hold the elevating units 107, 109 up. The latch382 is also connected by a link 385 to a solenoid 386 arranged to beenergized to release the arm 380 when the detector 24 is tripped uponpassage of the trailing edge 111 into the upper folding unit asdescribed. As illustrated in Fig. 2, the fourth fold tucker arm 124 isconnected to its operating unit 194 by a link 388 and a two-armed lever390 pivotally mounted at 391, the second arm 392 having a roller 393cooperating with the cam 394.

Referring now to Fig. 24, the wiring diagram for the presentsheet-folding machine includes the photo-sensitive detectors 14, 16, 28and the magnetic-clutch timing mechanisms 198, 199, 201 associatedtherewith and operatively connected to their respective solenoids 234,234a, 23% forming a part of the tucker operating units 134, 136, 194 forthe first, second and fourth folding stations respectively. The wiringdiagram also includes photo-sensitive detector 24 operatively connectedto solenoid 234c forming a part of the transfer or third fold tuckeroperating unit 138. Since each folding unit for performing the first,second and fourth folds is similarly connected in the diagram, it isbelieved that a description of the wiring for the first folding unitwill snfiice for each.

As herein shown, the photo-sensitive detector unit 14 is connected tothe main-power supply lines 400, 401 through leads 403, 404, and adirect-current circuit connecting the detector unit 14 with themagnetic-clutch unit 198 may be supplied with power from a transformer406 through leads 408, 409, the transformer being connected to the mainlines by leads 410, 411. Each photosensitive detector unit is providedwith a switch 412 arranged to be actuated to close a circuit at contact413 to energize the slowly rotated magnetic-clutch element 266 when theleading edge of the sheet intercepts the light source, and to close acircuit at contact 414 to energize the faster moving magnetic-clutchelement 268 when the light source is again exposed by passage of thetrailing edge of the sheet beyond the detector unit.

In operation when the leading edge of the sheet intercepts the lightsource, the circuit is closed through leads 408, 415, switch contact413, and lead 416 to one side of the magnetic-clutch element 266, thecircuit being continued on the other side of the clutch element 266through leads 417, 418 and 409 to complete the circuit and effectrotation of the timing cam 250 at a slow rate of speed. As soon as thecam 250 starts to rotate, the normally open stop switch 254 is closed,and when the trailing edge of the sheet passes beyond the detector toagainexpose the light source, the circuit is opened at contact 413, anda circuit is established through leads 408, 415, contact 414, lead 419,stop switch 254, lead 420, through relay contacts 422, and leads 424,426 to one terminal of the magnetic-clutch element 268, the circuitbeing completed through lead 428 from the other terminal and leads 418,409 to the transformer 406, thus effecting rotation of the cam 250 atthe faster speed,

1 1 as described. The'relay, indicated a't 430, may comprise a telephonetype electromagnetic relay, and-in operation when the normally openlimit switch 258 is closed' momentarily by the cam 259, as indicatedinFig. 23Lthe' relay 430 is closed by lead 420 from the closed stopswitch 254 through limit switch leads 431, 433 to one terminal of therelay 430, and from theother terminalthrongh leads 435, 418', 409 to thetransformer 406. The relay is held closed by the holding contacts 432 ofthe relay 439, as indicated in Fig. 24. Simultaneously therewith, thecircuit is opened at relay contacts 422 so thatthe current to thefast-moving clutch element 268 is shunted through a resistor 434' forthe purpose of reducing the clutch-holding strengthduring-the remainderof' the rotation of the cam 250' to its stop position, as

will be described. Operation of the relay 430 is also arranged to closecontacts 436 in acircuit including an auxiliary relay 438 and a chargedcondenser 440,- the auxiliary relay 438 being arranged to be momentarilyclosed by the charge on the condenser 440. The'aiixiliary relay in turnis arranged to close atucker solenoid switch 442 to energize thesolenoid 234to" enable the tucker operating unit 134 to perform thefolding-opera= tion. The solenoid 234 forms part of a circuit connectedto the main leads and includes leads 444', 446frm the main lead 400 toone terminal of the solenoid, then through switch 442 connected to theother terminal and leads 448, 458 and 451 back to the main lead 401;

In practice it is desired to have the solenoid -234operate as quickly aspossible, that is, to be'energized'and particularly to be thereafterrapidly deenergized to'effect' release of the one-revolution clutch200and operation of the folding unit 134, the rapid deenergization beingdesirable to effect quick return of the release arm 222 toclutch-disengaging position so as to prevent more than one revolution ofthe clutch 200 each cycle of operation. This is accomplished by means ofthe auxiliary relay 438 which is only momentarily closed'by'thestored'charge of electricity on the condenser 440 to close-the solenoidswitch 442, and in practice the charge onthe condenser 440isquickly'discharged so that the solenoid 234 is ener gized onlymomentarily, the discharge of the condenser elfecting deenergization-ofthe auxiliary'relay 238 and deenergize the solenoid 234 P opening of theswitch 442 to in a minimum time. The condenser 440 is permitted 'to berecharged between cycles of operation-by means of a selenium rectifier452, the charging circuit including-- 185d leads 444, 453 through theselenium rectifier 454, and resistor 455 to one terminal of thecondenser 440. The circuit is continued from the condenser through leads448, 45% and 451 as shown. 7

During the continued rotation ofthe magnetic clutchelement 268 the cam2-50 opens the circuit at the stop switch 254, thusdiscontinuingoperation of the magnetic clutch unit and deenergizing therelay 430. A'sabove described, during the latter portion of rotation ofthe cam disk 250, the current to the magnetic-clutch unit 268- isshunted through the resistance 434 which reduces the field current onthe magnetic element 268enabling it to continue its rotation of thecam250 but deenergizing'the magnetic element sufficiently so that whenthe cam'reaches the stop position the residual magnetism will be'so lowthat the cam will come to rest withth'e roll'252 seated in the cutout251 of the cam, as shown in Fig. l8,in'readiness for a succeedingcycleof'operation.

The second and fourth folding stations 18'and 3tlar'e similarly operatedthrough similar wiring connections" from the main leads 400, 401 asindicated in Fig.241 The" transfer or third fold operating'unit' 138 isarranged to'be operated immediatelyupon' detection of the leading edgeof the twice-folded sheet byth'e photo-sensitive detector" 24. As shownin Fig. 24,'the solenoid 234c isincluded inf a circuit'comprising leads444, 456, solenoid234c',"switch" 458and leads 460,451, and in practicethe SWltCh QSS'iS arranged to be momentarily "closed an auxiliary relaydetector 24; the detector switch is closed at contact 466 to energizethe" auxiliary relay 462 to-effect' momentary closing of switch 458topermit operation of the transfer operating'me'chanisrn 138 for onerevolution, as described. The condenser 464- may be recharged betweencycles of operation through a" circuit'connected to the main lead 400through le'ads 444", 453, selenium rectifier 452, lead 474; resistor 475and lead 465 to the condenser 464, the

circuit being continued from the'condenser through lead 451 to themainlead 401.

' As previously described, the elevating linkages 107, 109 anmaintaining the sheet being transferred above the moving belts ZOduringthe transfer operation are latched in'their elevatedpo'sition by thelatch member 382' connected to the solenoid 386. As shown in Fig. 24,the solenoid 386 is included in a circuit from the main line comprisingleads 444, 478 to the solenoid 386; the'circuit being continued throughthe solenoid switch 380, leads 481; 471 and 451 to the mainline. Theswitch 480 is arranged to be momentarily closed by an auxiliary 482which is provided in a circuitincluding: a charged condenser 484 andarranged to'be' closed through detector switch contact 486. Thus, whenthe trailing edge 111 of the'sheet passes off the elevating linkage intothe upper folding section 26 to again expose the light source to thedetector 24, the detector switch is'closed at contact 486 to energizethe auxiliary relay 482'and effect momentary closing of the switch 480to energize the latch-release solenoid 386 and permit the elevatinglinkages 107, 109 to be returned to their lowered position, asdescribed. The condenser 484 may be recharged through the seleniumrectifier 452-and resistor 488' during the time between cycles ofoperation.

A switch 490 may be provided for each operating unit whereby to renderinoperative one or another of the units while permitting operation ofthe remaining units.

From. the above description'it will be seen that the presentsheet-folding machine is capable of operation upon sheets of varyinglengths to effect automatic foldingof the sheet at a predetermined pointin its length as determined bythe novel control mechanism' includingphoto-sensitive detecting means actuated by the leading 1. In asheet-folding machine for folding sheets of' varying lengths, incombination, sheet-folding means, means for advancing a sheet intooperative relation to the folding means, and control means including asingle photo-sensitive detector disposed at fixed distance in advance ofsaid folding means fordetecting the passage of the leading and trailingedges of the sheet being advanced into folding position, a difi'erentialtimer responsive to said detector for actuating said folding means, saidtimer including a cam operative through a distance related to .saidfixed distance and to the rate of advance of the sheet and having twomagnetic clutches selectively responsive to said single detector forcooperation with said are, means for driving said clutches at differentspeeds relative to the'advance of the sheet, one of said clutches beingdrivenat areduced rate proportionate to the division to i be made by thefold when said leading edge intercepts the detector, the other clutchbeing driven at a rate corresponding to the advance of the sheet whenthe trailing edges pass the detector whereby to effect folding of thesheet at a predetermined point in the length of the sheet, said timercam being mounted intermediate said magnetic clutches and adapted to beselectively attracted to one and then the other thereof upon passage ofsaid leading and trailing edges respectively, a limit switch cooperatingwith said cam and circumferentially adjustable relative thereto arrangedto actuate said folding means when the sheet has been advanced intooperative position to be folded, and a fixed stop switch cooperatingwith said cam for discontinuing the operation of said timer at the endof one revolution to terminate a cycle of operation.

2. In a sheet-folding machine of the character described, sheet-foldingmeans including a one-revolution clutch, and a circuit including a timerand a solenoid arranged to be energized by said timer for releasing saidone-revolution clutch, and an auxiliary relay circuit for operating saidsolenoid having a charged condenser arranged to operate the auxiliaryrelay whereby to effect rapid deenergization of said solenoid to preventmore than one revolution of said clutch, and means for recharging saidcondenser between cycles of operation.

3. In a sheet-folding machine of the character described, means forsupporting and continuously advancing a sheet to be folded, a firstsheet folding unit including a tucker member operative to form atransverse fold relative to the direction of advance of the sheet, asecond sheet-folding unit cooperating with said first unit and includinga pair of cooperating rolls disposed above said advancing means and atucker member operative to form a longitudinal fold relative to thedirection of advance of the sheet, said second tucker member effectingtransfer of the sheet from the advancing means to said rolls of thesecond folding unit, control means including means for detecting theleading edge of a sheet to be transferred for actuating said secondtucker member, and elevating means operating simultaneously with saidtransfer operation for bodily elevating the entire sheet above saidcontinuously advancing means whereby to terminate forward movement ofthe sheet during the transferring and folding operation.

4. A sheet folding machine as defined in claim 1 wherein the cam isprovided with magnetic contact disks, and relatively thin brass spacersbetween the contact disks and their respective magnetic clutches wherebyto reduce the effects of residual magnetism when one magnetic clutch isdeenergized and the other energized.

5. A sheet folding machine as defined in claim 1 wherein the sheetfolding means includes a cam for operating said folding means, a onerevolution clutch adapted to permit rotation of said cam, and solenoidoperated means actuated by said timer for releasing said clutch.

6. In a sheet folding machine of the character described, incombination, means for supporting and continuously advancing a sheet tobe folded, sheet folding means including a pair of cooperating rollsdisposed above said advancing means, and an elongated tucker memberarranged to transfer the sheet from the continuously advancing means tosaid rolls to form a longitudinal fold relative to the advance of thesheet, and means for bodily elevating the entire sheet above the levelof the advancing means to terminate the forward advance of the sheetduring the transfer operation.

7. In a sheet folding machine of the character described, incombination, a first sheet folding unit including means for supportingand continuously advancing a sheet, and means for forming one or moretransverse folds in a sheet moved therealong, a second sheet foldingunit disposed above said continuously advancing means for forming a foldat right angles to said transverse folds, an elongated tucker memberarranged to transfer the sheet from the advancing means to said secondsheet folding unit, and means for bodily elevating the entire sheetabove the level of the advancing means to terminate the forward advanceof the sheet during the transfer operation.

8. In a sheet folding machine of the character described, incombination, a first folding unit including means for supporting andcontinuously advancing a sheet, and means for forming one or moretransverse folds in a sheet moved therealong, a second sheet foldingunit disposed above said continuously advancing means for forming a foldat right angles to said transverse folds, an elongated tucker memberarranged to transfer the sheet from the advancing means to said secondsheet folding unit, means for bodily elevating the entire sheet abovethe level of the advancing means to terminate the forward advance of thesheet during the transfer operation, and control means including meansfor detecting the leading edge of a sheet to be transferred foractuating said tucker member and said elevating means, means forretaining the elevating means in its raised position after the tuckermember is lowered, and means responsive to the passage of a trailingedge of the sheet being transferred beyond said detecting means forreleasing said retaining means.

References Cited in the file of this patent UNITED STATES PATENTS1,687,587 Pearne et al Oct. 16, 1928 2,034,040 Johnson Mar. 17, 19362,280,954 Kahn Apr. 12, 1942 2,291,487 Myers July 28, 1942 2,308,155Clegg Jan. 12, 1943 2,330,977 Johnson Oct. 5, 1943 2,374,779 Preston May1, 1945 2,458,544 Watson Jan. 11, 1949 2,545,798 Sjostrom Mar. 20, 19512,572,472 Gn'flin Oct. 23, 1951 2,652,246 Kagan Sept. 15, 1953 2,659,598McLagan Nov. 17, 1953

